This application claims the priority of German Application No. 197 25 351.2, filed Jun. 16, 1997, the disclosure of which expressly incorporated by reference herein.
The invention relates to a control device for operating a window wiper in a motor vehicle and, more particularly, to a control device having a switching device for the selection of several wiping functions, a sensor device for determining a wetting degree of a window, and an electronic analyzing system. The window wiper is capable of being operated, depending on the wiping function selected by the user, in a continuous wiping operation and/or in a single wiping operation. The electronic analyzing system, during a first wiping function, analyzes the determined wetting degree of the window and, depending on the determined wetting degree of the window, in a continuous wiping operation, sets a wiping frequency and/or, in a single wiping operation, activates a wiping cycle for the window wiper.
The window wipers in a motor vehicle have the purpose of providing the driver with an optimal view through the windows during precipitation. The driver's most important viewing direction is toward the front through the windshield. The windshield is normally cleaned by means of at least one windshield wiper which comprises a wiper arm, a wiper motor, a wiper gear and a wiper linkage, in which case the wiper arm can be driven in a continuous operation with fixed wiping frequencies. In addition, as a rule, a single wiping operation can be selected which, when a switching device is operated, carries out a one-time wiping operation, and/or an intermittent function can be selected which carries out a wiping cycle with a defined wiping cycle duration and with defined pause periods between two wiping cycles.
It is stipulated by law that the window wipers of window wiping systems must operate at at least two wiping frequencies, in which case one wiping frequency must comprise more than 45 wiping cycles per minute. The second wiping frequency must not amount to less than 10 wiping cycles per minute and to more than 55 wiping cycles per minute. The difference between the largest and the smallest wiping frequency must amount to at least 15 wiping cycles per minute. In the case of the intermittent operation, it must be ensured that at least 10 wiping cycles per minute are carried out.
In the case of window wipers, the basic problem arises that, on the one hand, a wiping frequency for the wiper arm should be selected which is as low as possible because the wiping result improves with a decreasing wiping frequency, but, on the other hand, the wiping frequency must not be selected too low because then so-called slip stick effects will occur which are exhibited by a pronounced rattling and jumping of the wiper arms. The wiping frequency of the wiper arm is limited in the upward direction by the deterioration of the wiping results because of aquaplaning effects and by the design of the wiper motor. Since, as a rule, the involved wiper motors are not rotational-speed-controlled, it is an additional factor that the wiping frequency of the wiper arm will change when loaded, for example, by wind effects, the degree of dryness of the window or by snow.
German Patent document DE 40 00 735 A1 discloses a control device of the above-mentioned type for the operation of a window wiper, having a switching device for selecting a wiping operation, having a sensor device for determining a wetting degree of a window and having an electronic analyzing system, in which case the window wiper can be operated in a continuous wiping operation and/or a single wiping operation. In the case of an automatic wiping operation, as a function of the determined wetting degree of the window, the electronic analyzing system switches between the continuous wiping operation and the single wiping operation, in which case, as function of the determined wetting degree of the window in the continuous wiping operation, a wiping frequency is adjusted and in the single wiping operation, a wiping cycle for the wiper arm is activated.
It is considered to be a disadvantage in this case that no measures are provided for operating the window wiper in the automatic wiping operation if the sensor device fails or operates defectively.
European Patent Document EP 504 606 B1 discloses a control device for the operation of a window wiper in the case of which different wiping operations can be set by means of an operating-type switch. In this case, by means of another operating element, automatic functions can be activated which change the pause periods in the intermittent operation and the wiping frequency in the continuous operation as a function of the vehicle speed and/or the degree of wetness detected by means of a rain sensor. In addition, as a function of the set wiping operation, by means of a preselecting element, several pause periods for the intermittent operation and several wiping frequencies for the continuous wiping operation can be manually adjusted.
It is considered to be a disadvantage in this case that operation of the window cleaning system requires high expenditures of time, whereby the user's attention may be diverted from the traffic situation. In addition, because of the use of several operating elements, the suggested solution is expensive.
It is an object of the present invention to improve the operating comfort of a window cleaning system of the above-mentioned type and carry out the control of the window cleaning system at reasonable cost, and to ensure an appropriate operation of the window wiper in the event of a defect.
According to the invention, this object is achieved by a control device having a switching device for the selection of several wiping functions, a sensor device for determining a wetting degree of a window, and an electronic analyzing system. The window wiper is capable of being operated, depending on the wiping function selected by the user, in a continuous wiping operation and/or in a single wiping operation. The electronic analyzing system, during a first wiping function, analyzes the determined wetting degree of the window and, depending on the determined wetting degree of the window, in a continuous wiping operation, sets a wiping frequency and/or, in a single wiping operation, activates a wiping cycle for the window wiper. The electronic analyzing system sets the wiping frequency of the window wiper in the continuous wiping operation during the first wiping function within a first wiping frequency band (f.sub.1u to f.sub.2o), during a second wiping function, within a second wiping frequency band (f.sub.1u to f.sub.1o), and during a third wiping function, within a third wiping frequency band (f.sub.2u to f.sub.2o), depending on the analysis of the wetting degree of the window 1. The actual wiping frequency being set is as low as possible. If, during the switching between the wiping functions, a change of the wiping frequency band is required, the actual wiping frequency, during a change from the second wiping frequency band (f.sub.1u to f.sub.1o) to the third wiping frequency band (f.sub.2u to f.sub.2o) is increased by a defined number "n" wiping cycles per minute or, during a change from the third wiping frequency band (f.sub.2u to f.sub.2o) to the second wiping frequency band (f.sub.1u to f.sub.1o) is reduced by a defined number "m" wiping cycles per minute. Further advantageous developments of the invention are described herein.
The main idea of the invention consists of providing, for the operation of a window wiper, a switching device with four switching positions for the selection of a wiping function ("off", "optimized wiping", "continuous wiping step 1", "continuous wiping step 2") by the user, as well as a sensor device for determining a wetting degree of a window. In order to achieve an improved wiping result, by means of an electronic analyzing system, which analyzes the wetting degree of the window determined by the sensor device, an automatic continuous or step-by-step adaptation of the wiping frequency to the wetting degree of the window is carried out within the wiping function selected by the user.
During the "continuous wiping step 1" wiping function in a continuous wiping operation within a second wiping frequency band, for example, between f.sub.1u =33 and f.sub.1o =45 wiping cycles per minute, and during the "continuous wiping step 2" wiping function in a continuous wiping operation within a third wiping frequency band, for example, between f.sub.2u =48 and f.sub.2o =60 wiping cycles per minute, the wiping frequency is adaptable to the wetting degree of the window. The second and the third wiping frequency bands may adjoin one another directly, may partially overlap or may be separated from one another. During the adaptation of the wiping frequency to the wetting degree of the window, the electronic analyzing system attempts, by means of an electronic triggering system which may be part of the electronic analyzing system, to set a wiping frequency which is as optimal as possible, for example, a wiping cycle duration which is as long as possible. During the "optimized wiping" wiping function, the wiping frequency during a continuous wiping operation within a first frequency band, which comprises the second and the third wiping frequency band, can be changed, for example, between f.sub.1u =33 and f.sub.2o =60 wiping cycles per minute.
In addition, within the "optimized wiping" wiping function, a single wiping operation is provided, in which case, in the single wiping operation, a wiping cycle and/or the duration of the wiping cycle is activated as a function of the wetting degree of the window and/or is set by the electronic analyzing system. For the adaptation of the wiping frequency in the continuous wiping operation or for activating a wiping cycle in the single wiping operation, a signal of the sensor device, which is constructed, for example, as an optical rain sensor, is used and is analyzed in the electronic analyzing system. The rain sensor supplies a signal which is dependent on the wetting degree of the window, in which case it must be ensured that the rain sensor is situated in the range of the wiping field. By this measure, the operation of the window wiper can be adapted to the wetting degree of the window and thus to the intensity of the precipitation. The use of the switching device with four switching positions has the advantage that a user can operate the window cleaning system in the usual manner.
In addition, the electronic analyzing system ensures that, in the event of a failure or a malfunctioning of the rain sensor, the operation of the window wiper corresponds to the legal regulations, in that, in the event of a failure or a malfunctioning of the rain sensor, the electronic analyzing system during the "optimized wiping" wiping function, sets the duration of a wiping cycle and the pause duration between two wiping cycles such that at least 10 wiping actions per minute take place; for example, the pause duration is set to be fixed at 4.5 seconds and the duration of the wiping cycle is set to be fixed at 1.5 seconds--this would correspond to a wiping frequency of 40 wiping cycles per minute in the continuous wiping operation. During the "continuous wiping step 1" wiping function, the electronic analyzing system fixedly sets a first wiping frequency, for example, 40 wiping cycles per minute, and during the "continuous wiping step 2" wiping function, it fixedly sets a second wiping frequency, for example, 55 wiping cycles per minute. This ensures an appropriate operation of the window cleaning system even in the event of a failure of the rain sensor. In this emergency operation, the user can make a selection between the "off" wiping function (operation of the window wiper switched off), the "optimized wiping" wiping function with a fixedly set intermittent operation, the "continuous wiping step 1" wiping function with a fixedly set first wiping frequency, and the "continuous wiping step 2", wiping function with a fixedly set second wiping frequency. The failure or the malfunctioning of the rain sensor can be determined during an internal system monitoring, which takes place, for example, automatically after each vehicle start, for example, through the use of the electronic analyzing system.
During normal operation, when it starts to rain, the user can select a wiping function by operating the switching device, for example, by rotating a steering column shift lever.
When the switching device is switched from the switching position 0 ("off" wiping function) into the switching position 1 ("optimized wiping" wiping function), if the analysis of the sensor signal of the sensor device is also carried out in the switching position 0 ("off" wiping function), as a function of the wetting degree of the window, an optimal wiping operation (single wiping operation or continuous wiping operation) with an optimal wiping cycle duration in the single wiping operation or an optimal wiping frequency in the continuous wiping operation is set via the electronic analyzing system. If the analysis of the sensor signal takes place only in the switching positions 1 to 3, after the switching from the switching position 0 ("off" wiping function) to the switching position 1 ("optimized wiping" wiping function), a wiping cycle is carried out with a defined wiping cycle duration, for example, 1.5 seconds--this corresponds to a wiping frequency of 40 wiping cycles per minute in the continuous operation. Subsequently, the electronic analyzing system analyzes the sensor signal of the sensor device and an optimal wiping operation which is adapted to the wetting degree of the window with an optimal wiping cycle duration in the single wiping operation or an optimal wiping frequency in the continuous wiping operation is set by the electronic analyzing system. In this case, the analysis of the sensor signal by means of the electronic analyzing system takes place continuously or at regular intervals. Thus, in the "optimized wiping" wiping function, the electronic analyzing system can carry out, without any intervention by the user, all switching and/or adapting actions for the optimal operation of the window wiper in order to achieve an optimal wiping result as a function of the wetting degree of the window.
When the switching device is switched from the switching position 0 ("off" wiping function) into the switching position 2 ("continuous wiping step 1" wiping function), if the analysis of the sensor signal of the sensor device is also carried out in the switching position 0 ("off" wiping function), as a function of the wetting degree of the window, an optimal wiping frequency within the second wiping frequency band is set by the electronic analyzing system. If the analysis of the sensor signal takes place only in the switching positions 1 to 3, after the switching from the switching position 0 ("off" wiping function) to the switching position 2 ("continuous wiping step 1" wiping function), a first medium wiping frequency, for example, 40 wiping cycles per minute, is set. Subsequently, the electronic analyzing system analyzes the sensor signal of the sensor device and an optimal wiping frequency within the second wiping frequency band is set which is adapted to the wetting degree of the window.
When the switching device is switched from the switching position 1 ("optimized wiping" wiping function) to the switching position 2 ("continuous wiping step 1" wiping function), if the actual wiping cycle duration corresponds to a wiping frequency of the second wiping frequency band, this wiping frequency is taken over or, if the actual wiping cycle duration corresponds to a wiping frequency of the third wiping frequency band, this wiping frequency is reduced by a defined number "m" of wiping cycles per minute and is set as the new wiping frequency by the electronic analyzing system. If the actual wiping cycle duration corresponds to a wiping frequency which is between the second and the third frequency band, this wiping frequency is reduced by a defined number "z" of wiping cycles per minute and is set as the new wiping frequency by the electronic analyzing system. In this case, the numerical values "m" and "z" are set such that the new wiping frequency is within the second wiping frequency band. Subsequently, the electronic analyzing system continuously analyzes the sensor signal of the sensor device and sets an optimal wiping frequency within the second wiping frequency band which is adapted to the wetting degree of the window.
When the switching device is switched from the switching position 0 ("off" wiping function) into the switching position 3 ("continuous wiping step 2" wiping function), if the analysis of the sensor signal of the sensor device is also carried out in the switching position 0 ("off" wiping function), as a function of the wetting degree of the window, an optimal wiping frequency within the third wiping frequency band is set by the electronic analyzing system. If the analysis of the sensor signal takes place only in the switching positions 1 to 3, after the switching from the switching position 0 ("off" wiping function) to the switching position 3 ("continuous wiping step 2" wiping function), a second medium wiping frequency, for example, 55 wiping cycles per minute, is set. Subsequently, the electronic analyzing system analyzes the sensor signal of the sensor device and an optimal wiping frequency within the third wiping frequency band is set which is adapted to the wetting degree of the window.
When the switching device is switched from the switching position 1 ("optimized wiping" wiping function) to the switching position 3 ("continuous wiping step 2" wiping function), if the actual wiping cycle duration corresponds to a wiping frequency of the third wiping frequency band, this wiping frequency is taken over or, if the actual wiping cycle duration corresponds to a wiping frequency of the second wiping frequency band, this wiping frequency is increased by a defined number "n" of wiping cycles per minute and is set as the new wiping frequency by the electronic analyzing system. If the actual wiping cycle duration corresponds to a wiping frequency which is between the second and the third frequency band, this wiping frequency is increased by a defined number "z" of wiping cycles per minute and is set as the new wiping frequency by the electronic analyzing system. In this case, the numerical values "n" and "z" are set such that the new wiping frequency is within the third wiping frequency band. Subsequently, the electronic analyzing system continuously analyzes the sensor signal of the sensor device and sets an optimal wiping frequency within the third wiping frequency band which is adapted to the wetting degree of the window.
When the switching device is switched from the switching position 2 ("continuous wiping step 1" wiping function) to the switching position 3 ("continuous wiping step 2" wiping function), the actual wiping frequency is increased by a defined number "n" of wiping cycles per minute and is set as the new wiping frequency by the electronic analyzing system. Subsequently, the electronic analyzing system continuously analyzes the sensor signal of the sensor device and sets an optimal wiping frequency within the third wiping frequency band which is adapted to the wetting degree of the window.
When the switching device is switched from the switching position 3 ("continuous wiping step 2" wiping function) to the switching position 2 ("continuous wiping step 1" wiping function), the actual wiping frequency is reduced by a defined number "m" of wiping cycles per minute and is set as the new wiping frequency by the electronic analyzing system. Subsequently, the electronic analyzing system continuously analyzes the sensor signal of the sensor device and sets an optimal wiping frequency within the second wiping frequency band which is adapted to the wetting degree of the window.
When the switching device is switched from the switching position 3 ("continuous wiping step 2" wiping function) or from the switching position 2 ("continuous wiping step 1" wiping function) to the switching position 1 ("optimized wiping" wiping position), the respective wiping cycle duration of the actual wiping frequency is taken over. Subsequently, as a function of the wetting degree of the window, the electronic analyzing system sets an optimal wiping operation (single wiping operation or continuous wiping operation) with an optimal wiping cycle duration in the single wiping operation or an optimal wiping frequency of the first wiping frequency band in the continuous wiping operation.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.